As is well known, bursters have long been employed in the processing of continuous business form stationery. In the usual case, such stationery includes one or more plies of substantial length which may be separated into individual business forms, i.e., individual form lengths, along transverse lines of perforation extending across the ply or plies.
Such separation can, of course, be accomplished manually but such is time consuming and defeats, at least in part, one of the main purposes of the use of continuous business form stationery, namely, rapid processing. Consequently, there have evolved various types of apparatus commonly known as bursters which separate a continuous business form into individual form lengths at rapid speeds.
Typical continuous business form stationery has varying form lengths depending upon the use to which the document is to be put. For example, when payroll checks in continuous form are being processed, each individual form length will be relatively short, typically on the order of 3 inches. Conversely, documents or letterheads employed in mass mailings or the like will have form lengths on the order of 11 inches, and occasionally lengths up to 14 inches.
Because one user of continuous business forms may be processing forms of varying form lengths in the course of his business, it is desirable that bursting apparatus be capable of properly bursting all business forms used, regardless of the form length.
A typical burster employs two pairs of rollers, an outfeed pair and an infeed pair. In the usual case, the outfeed pair of rollers is rotated at a higher angular velocity than the infeed pair. As soon as a form passes through the infeed pair of rollers and is engaged by the nip of the outfeed pair, because of the higher peripheral speed of the rollers of the outfeed pair, a tensioning force is placed on the business form which causes the same to separate along the transverse line of weakening.
It will be readily apparent, however, that before such can occur, there must be but a single one of a line of weakening between the two pairs of rollers. If no such line of weakening is present, tearing or wrinkling of the form will occur. If two such lines of weakening are located between the two sets of rollers, partial separation on each of the lines may occur or, there may be no separation whatsoever on one of the lines of weakening with the consequence that the form is improperly burst in either event.
Thus, in order to compensate for varying form lengths, burster manufacturers have heretofore generally provided an adjustment in the apparatus whereby the spacing between the infeed pair of rollers and the outfeed pair of rollers may be selectively varied dependent upon the form length of the continuous business form to be burst. This approach is exemplified in, for example, U.S. Pat. No. 3,161,335 issued Dec. 15, 1964 to Pine et al. and U.S. Pat. No. 3,493,156 issued Feb. 3, 1972 to Absler et al.
While these constructions work extremely well for their intended purpose, because of the need to adjust the spacing between the pair of rollers, the cabinets for housing the bursters necessarily must be larger than would be the case if a constant space of but a few inches could be employed.
One attempt at providing a fixed spacing burster is described in U.S. Pat. No. 3,338,487 issued Aug. 29, 1967 to Schutz. Schutz employs fixed spacing between two sets of burster rolls and drives the outfeed rolls at a higher angular velocity than the infeed rolls. A slip clutch is located in the drive for the outfeed rollers so that such rollers could rotate at a speed approximating that of the infeed rollers when no line of weakening was located between the two pairs of rollers in an attempt to avoid tearing or wrinkling of the form.
While the Schutz construction worked well in many instances, various deficiencies were present.
In an attempt to cure such deficiencies, there then evolved a structure as disclosed in U.S. Pat. No. 3,672,551 issued June 27, 1972 to Peterson. Peterson eliminated the slip clutch in the outfeed drive in favor of a limited, variable, lost motion connection in the infeed drive. By varying the length of the limited lost motion connection, as more fully described in the Peterson patent, the apparatus could be adjusted for business forms of a wide variety of different form lengths and yet was quite compact, having the desired fixed spacing between the infeed and outfeed roller pairs.
The Peterson invention worked extremely well over a large variety of business form lengths. However, when subjected to extended usage, because of the nature of the limited lost motion connection, there occasionally resulted a parts failure in that connection which in turn would require more frequent servicing than would be desired. In addition, the nature of the adjustment of the length of the limited lost motion connection was such as to require a fair degree of effort on the part of the operator of the machine to the extent that unskilled labor could not be employed to operate the same in every instance.
The present invention is directed to overcoming one or more of the above problems and constitutes an improvement on the apparatus described by Peterson.